IRVING — As DeMarco Murray moves past another disappointment this week, he’s been faced with a reminder of the promise he once offered the Cowboys.

The dark times of the present have converged with his brighter past as Dallas prepares to face St. Louis, the team Murray carved up en route to establishing a single-game franchise rushing record as a rookie in 2011.

That game is now a distant memory — one that has faded away as Murray has failed to replicate a performance so grand. Last Sunday, Murray slogged through a 17-16 defeat to Kansas City, gaining 25 yards on 12 carries. The meager output was just the latest indictment of a ground game that has been a major weakness since the beginning of last season.

“I didn’t feel it today,” Murray said after the loss. “Just got to get better.”

There was a hint of frustration in Murray’s voice. These days, success has been hard to come by for the third-year veteran.

The last time he rushed for more than 100 yards was in the 2012 season opener. Since then, Murray has rarely been able to gain any traction while operating behind a shaky offensive line that has been unable to create running lanes on a consistent basis.

Despite the struggles, Cowboys coach Jason Garrett has professed his faith in Murray.

“Murray is our runner,” Garrett said. “We have a tremendous amount of confidence in him.”

Murray has been the team’s primary ball carrier since that October afternoon in 2011, when he rushed for 253 yards against a ramshackle Rams defense. The opportunity to make history that day materialized only because Felix Jones suffered a high-ankle sprain the week before against New England.

Although Jones was sidelined, Murray wasn’t even penciled in as the starter. Tashard Choice was.

But Murray was inserted into the game early in the first quarter, and on his first carry, he sprinted 91 yards for a touchdown. There was no turning back now. Choice had been pushed off stage, and the rest of the afternoon Murray dominated the Rams, going for 43 yards here and 19 yards there. Before the destruction of St. Louis was over in the 34-7 victory, he had shattered Emmitt Smith’s single-game Cowboys’ rushing record.

The following day Smith tweeted this missive: “In order to be the best, you must be consistent for a long time. Hopefully, this is the start of things to come.”

The statement was a cryptic one. And now, it seems to be prophetic. After all, Murray’s accomplishment, in retrospect, may not have been as great as it seemed at the time.

That season, the Rams had allowed Arizona’s Beanie Wells to run for 228 yards. Ryan Torain sliced up St. Louis, too, on his way to producing 135 rushing yards. Both players are now out of the league.

But in the weeks that followed, it was hard not to buy into the idea that Murray would be the Cowboys’ first elite running back since Smith. The following month, Murray gained 139 yards against Seattle and 135 more in a victory over Buffalo.

Yet just as Murray was closing in on becoming the first Cowboys player to rush for more than 1,000 yards since Julius Jones achieved that feat in 2006, he suffered a fractured right ankle in December 2011 and missed the final three games.

Things have not been the same for Murray. Last season, after a promising 2012 debut when he rushed for 131 yards in the opener, the running back failed to maintain any momentum. Good performances were outnumbered by bad ones.

Murray’s durability and availability also became an issue after he missed six games because of a sprained left foot. By the end of the season, he had become the face of a rushing attack that produced 1,265 yards — the lowest total in franchise history during a 16-game season.

“I don’t think that was very fair,” Daryl Johnston, the Fox analyst and former Cowboys fullback, said.

“He’s in a situation right now where he hasn’t been able to get into a rhythm and have the opportunity to carry the ball 20, 22, 25 times in a game. Whether it’s injuries he’s suffered … or a commitment to the run, there hasn’t been enough carries during the course of games to establish the rhythm.”

Garrett, Murray and offensive coordinator Bill Callahan have all said the Cowboys need to keep the ball on the ground more than 28.9 percent of the time, as Dallas has done in the first two games.

It makes sense to change their tack, not only to achieve greater balance but more important, to get victories. The Cowboys are 9-0 when Murray receives 20 or more carries and 4-12 in all other instances.

“Murray’s a good football player and has been his whole career, and he’s demonstrated that as a Cowboy,” Garrett said.

“I think it’s unrealistic to expect a guy to go out and break the franchise record every week, but when things go well, you want to take advantage of those opportunities. We’ve got to get our running game going. He’s a big part of what we want to do.”

He has been since that game against St. Louis two years ago — when Murray offered hope rather than disappointment that has defined his career as of late.

Follow Rainer Sabin on Twitter at @RainerSabinDMN

It’s all or nothing

The Cowboys have been most successful when running back DeMarco Murray has a heftier workload. Cowboys’ record based on Murray’s number of carries:

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